Philips Avalon CTS M2720A, Service Manual

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Range Definition 7 Troubleshooting
67
If the area of reach is not sufficient using the standard antenna supplied with the system, there are a few
things to consider initially:
– The placement of the antenna has an effect on the operating range. If it is located inside a metal cart
or other RF-absorbing material, then place the antenna externally by using the Antenna Extension
Mounting Kit (M2720A Option K01) to increase the range.
– Check the orientation of the antenna. In general, the antenna provides the greatest range when it is
positioned vertically.
– If the area of reach is still insufficient, consider installing an antenna system.
Range Definition
You can define the area of reach by performing a walk-test, either carrying a fluid-filled bag with the
transducers attached to it, or by wearing the transducers. The fluid-filled bag has the advantage that it can
be placed in various positions (for example, in a bath tub) which would not be so practical for the tester.
The area of reach can be determined by observing how far from the base station the transducers will still
work normally allowing continuous monitoring. The testers can communicate with each other using
appropriate communications equipment (for example, walkie-talkies).
There are two ways to define the area of reach:
• Watching the indicator/warning lamps on the base station.
• Watching the Received Signal Strength Indicator (RSSI) using a PC and the Service Support Tool.
(Refer to the Service Support Tool Help for more details.)
Using the Base Station
How to proceed:
1 Connect the base station to the fetal monitor.
2
Switch on the fetal monitor’s recorder.
3 Register the transducers to the base station, so that they are active. Wait until the slot’s right-hand lamp
goes to green.
4 Take out the transducer and check for a good RF link. The lamp should be continuously on.
5
Walk with the transducer to cover the area intended for monitoring.
6
If you see the signal loss warning lamps blinking, then you are near the limit of the effective
operating range of the system in the environment in question. Also, check for frequent mode
annotations on the recorder trace. Loss of RF signal will show as dropouts on the recorded trace. This
also indicates that you are close to the operating limit of the RF signal range.
7 Come back a short distance (say one meter/three feet at a time) until the signal loss warning lamps
stop blinking, the RF link lamp is continuously on, and a reliable recorder trace
without frequent dropouts is obtained.
8 Repeat to cover the whole area of intended operation. This is the limit of the range where the system can
transmit and receive parameter measurements reliably.
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